Detector for wireless apparatus.



B. 'J MIESSNER. DETECTOR FOR WIRELESS APPARATUS. APPLIOATIQN FILED 00125, 19110v Y 1,1 04,0659 I Patented- July 21, 191$ 2 SHBETS-SHEET 1 B. J. MIESSNER. I DETECTOR FOR WIRELESS APPARATUS.

' APPLICATION FILED OCT. 5, 1910.

Patented Ju1 21; 1914.;

. -2 SHEETS-SHEET 2.

BENJAMIN J. MIESSNER, OF YVASHINGTON, DISTRICT OF COLUMBIA.

Darn-ores non WIRELESS ArPAnA'rUs.

Specification of Letters Patent.

Patented July 21,1914.

Application filed October 5, 1910. Serizil No 585,484.

To all to]: am it may concern Be it known that I, BENJAMIN J. Minssisnagacitizen of the United States, residing at ll asl ington, in the District of Columbia,

have invented certain new and useful Immovements in Detectors for lVireless Apparatus, of which the following is a specification.

lily invention relates to improvements in detectors for wireless telegraphy apparatus.

The object of my invention is to provide a detector which will be sensitive in action, durable under the usual conditions of operation on land and sea and at the same time capable ofholding its adjustment well.

I have found that a wireless detector comprising crystalline material as one contact and a fine metallic point touching said crystalline material with a very light pressure as the other contact forms a combination which is particularly sensitive in receiving the wireless signals. This is particularly the case when the contact device consists of iron pyrites and a very light spring having a sharp point in light but continuous contact with the iron pyrites. \Vhile it is not impossible to obtain the desired light pressure of the contact between the mineral and metallic contact devices by carrying the metal contact point on the end of a very light helical spring, yet a detector made merely in this way while having great advantages over previously known detectors as to scnsitivencss to signals is too sensitive to mechanical vibrations for use on ship board or on land where such vibrations may occur. Therefore I have devised a particular method of mounting the metallic contact point so as to obtain the desired very light. pressure of the contact devices without the employment of a spring so light as to be readily vibrated by the usual jars, shocks or other mechanical vibrations to which receiving apparatus is liable to be subjected in normal use. This novel. construction constitutes an important feature of my invention, and broadly considered consists in so arranging a spring device carrying the metallic contact point that the yielding thrust of the spring on the said pointwill tend to urge said point in a direction at an lnchne to the plane of the general surface of the mineral contact device. A force acting in this manner on the point may he considered as resolved at the surface of contact ini o two components one of which is parallel to the plane of the surface of-the mineral at the point of c ntact, and the other at right angles thereto. The first named component merely tends to force the metallic point along the plane of the surface of the mineral contact device, while the other component is resisted by the mineral device and thereby pressure of the contacts against each other is produced. The greater the angle of inclination of the line of thrust of the spring, the less the pressure between the contacts. Hence by this arrangement a very light pressure may be obtained with a relatively strong spring, whereby the spring will be less easily affected by mechanical vibration. It-is true, of course, that when the mineral contact device consists of a fractured mass of crystals or crystalline material the fractured surface does not, strictly speaking, lie

wholly in one plane. However, the deflections of the elemental portions of the fractured surface from the general plane of: the

Whole material. are usually not excessively. great and therefore by making the 1nclination of the line of thrust of the spring about 45 to the general surface of the crystalline mass itwill result in practice that such line of thrust will in almost every case be at sullicicnt incline to the plane of the elemental surface of the mineral contact device with which the metallic contact point engages. lVith thisgcneral introduction my invention will now be described more particularly in connection with theaccon'ipanymg drawings in which:

Figure 1 is a side elevation of an apparatus embodying my invention; F1g. 2 a planview of the same; Fig. 3 an enlarged detail view of oneof the contact devices and its ad ustmg means; Fig. 4 1s a diagrammatic view showing the preferred manner of con necting my detector in the oscillating circuit; Fig. 5 is a diagram intended to illustrate on a large scale a metallic contact point placed against a mineral contact device and explaining themesohitions of the thrusting force of the spring; and Fig. 6 is an end .view of the detector disk.

Referring first to Fig. 5 letit be assumed that the line A indicates the surface or a crystalline or other mineral contact device, B a metallic point, and G a spring carrying said contact point and tending to press said point'in the direction of thearrow 0 with a force whose intensity is indicated by the length of said arrow. This force may then.

be resolved into two forces, namely a component parallel to the line A, whose intensity and direction are indicated by the arrow a, and a component at right angles to the line A whose direction and intensity are indicated by the arrow 1). The latter component indicated by b is the one which repre sents the pressure between the contact devices, and as will appear from the diagram is always less than the pressure of the spring indicated by the'length of thearrow c. The other component tends to force the contact oint in' the direction of the arrow a and is resisted by the friction between the two can tact-devices. If the component a is greater than the frictional resistance the contact point will move in the direction of the arrow a and thereby thespring will be bent or de-.

I fiected laterally to an extentsuficient to as i produce a counteraction opposing the de As the counteraction or re action of he sprlng laterally increases with liJS'dGfiQCtIOII a point will soon be reached where the component acting in the direction of the arrow a is in equilibrium with the reaction of said spring. This has the advantage of putting the spring under a slight tension in a direction at an angle to its line of thrust so that mechanical yibrations such as would be usually encountered on board ship cannot swin the spring laterally to break the contact between the contact point and the mineral contact device.

Referring now to Figs. 1, 2 and 3, D is the base plate, E and F suitable standards and G- a rotatable disk, cup-shaped on one face, in which cup is secured a plurality of aggregated crystals or portions of iron pyrites, these crystals being held in the cup by a suitable material of a metallic nature such as tin or low-melting alloy, of the kind usually employed for this purpose, all pursuant to U. S. patent to Pickard, No. 877,451 of January 21, 1908. The disk (iis provided with an axis 9 passing through a hole in the upper end of the standard E and capable of being secured in said standard by means of a set screw 9. The disk G, and its axis g are of suitable conductive material and are in electrical connection was a binding post H which forms one of the terminals to which is connected the oscillatingcircuit. The standard F is pro" yide'dE- at itsupper end with an angular-1y moi-nee.

adjustable head F having an opening through which passes a tube or cylinder l; capable 01' adjustment axially in the standard F and arranged to be secured at any desired point by means of a set screw 70. in order to permit'thc angular adjustment of the head. if it is provided with a pin F inserted in hole in the upperpart the standard F,

The tube K has one end closed by a head is and within said tube is arranged a small piston L mounted on the end of a stem .1 which extends through the head it and is provided at its outer end with a milled hard rubber hand wheel L The stem L within the tube i is surrmindcd by a helical spring If one end of which bears against the piston L and the other end against, the head is. The outer end of the piston L is provided with a. conical nose L which has its extreme outer point eccentric to the piston L. Upon the nose L" is secured a helico-spiral spring U which extends beyond the end oi the nose and terminates in a st 'aight portion Z. This spring L {its somewhat loosely on the nose L" and is secured at its inner end to said nose. The tube K, the piston L, the nose L and the spring L are of suitable conductive material, the spring If being preferably of spring brass wire about No. 30 gage. The axis of the tube K "is in line with the axis of the disk G and. the crystals of iron pyrites G are preferably arranged in a circle on the disk G. (Ewing to the eccentric arrangement of the end of the nose L a rotation of, the piston .L by means of the hand wheel L will cau'se theiree end of thev straight portion 9 of the spring-U to move .in a circle which is substantially of the same diameter as the circle of crystals. Further-' more, the straight portion Z of the spring L not only eXtends-to'wardthe crystalsbut also slopes outward at an incline. The spring L is in. electricalcommunication withthe binding post M which forms the second terminal of the device to which the oscillating circuit is connected.

While it is possible for a short time to employ a metallic contact point of any suitablemetal I prefer to make the same of some extremely hard, good conducting, nonoxidizable metal or substance such as iridium, iric'li.um-osmium alloy or platinum in order that it may not be oxidized by very strong sparks, The contact point may. be attached to the spring in the usual way by hard soldering. I have found that it is of great importance that the surface of metal in contact with the crystal. be very small and therefore the point should be very sharp. By rotating the disk G or the hand wheel L or both, the contact points may be brought in. contact with any desired one of the plurality of crystal masses or with any particular part rinses of one of said masses. The manner of ad- JHStDiOIllZ is as follows: The tube or cylinder being in line with the axis of the disk it IS moved forward so that, the contact point touches some one of tne'crystals with a slight p essure whereupon the set screw is tightrned to hold it in this position. The point is then drawn back from the crystals by means of the hard rubber handle and the disk G may be rotated as desired to bring any crystal which it is desired to use into the desired position. The point is then swung either laterally or rotated as may be desired to bring it against said crystal or' mass of crystals. Then by feeling about on clii'terent portions of the crystalline mass the most sensitive spotmay be found by noting the intensity of incoming; signals, or preferably the intensity of signals produced by a testing buzzer whichis generally employed. I have found that when a slight external potential (.02 to .3 volt) is applied to the detector through the telephone the sensitiveness of the detector is materially increased. I urthermore the current should flow in the direction from the metallic contact point to the mineral contact device in i order to secure the bestresults. The potentiometer should have a ery line graduation so that the potential may be adjusted very closely. This is highly important. It has ieen found by me that difierent oints' on the crystals usually require a di erent adjustment of the local battery potential in order to secure the best results. After a sensitive spot is" found the potentiometer may be quickly adjusted- In. practice I' have found that the whole operation of ad-. justing the detector to a sensitive condition should not require more than half a minute. 'I do not wish it to be understood that my improved detector is. absolutely immune from injury by excessively strong electrical disturbances in the vicinity of the station but it will be entirely unaffected by any such disturbances which are not sufficient to make the operation of wireless apparatus dangerous. Signals from powerful stations within a distance of one mile and from ship stations within a few hundred feet and atmospheric discharges during which it is possible to communicatehave practically no affect. upon this detector. l urtherinore it has been found under actual working conditions that this detector is far superior in this respect and equal in sensitivencss to all other detectors with which I am acrpiainted. Of the iron pyrite crystals some are unsuitable for use inthis ddtertor and therefore it is advisable in obtaining such crystals to test them for sensitiveness, then to select such as are sensitive, fracture them in order to have a fractured COIlttl'JL surface and test each of the portions before embedding it in the 311531 in the cup. It has been found that when a detector is fittedwith but one'crystal and constantly subjected to very strong'si'gnals.

the crystal will in time become fatigued, for

example, after half a day but ifallowed to rest a day or longer such a fatigued crystal will usually again regain its former sensitiveness. It is for this reason that a plurality of crystals are embedded in the disk I have also found that it is advisable to make the spring by taking a piece of No. 30 gage brassor copper wire and flattening the said wire as by rolling the same, thus giving the wire a rectangular cross section.

When the spring is formed in this way the In this way the straight portion is rela- 85,

tively stiff in a transverse direction f and hence-not easily affected by lateral mechanical vibrations. Vhile the resilient contactsupporting means is thus of relatively very small mass, it has nevertheless sufiicienteo stiffness to prevent its being unduly vibrated by disturbances to which it is exposed in practical use. l i

For tropical countries and wherethe atmosphere is extremely humid, it; is advan- 9.5

tageous to have the crystalline surface covered with a film of oil, in order to prevent short-circuiting or leakage.

} Having thus fully described my invenI tion, what I claim is:

1. A detector for Wireless apparatus comprising two contact devices, one consisting of a sensitive contact member, and the other 'of a metal point. and-resilient means of relatively very small mass for lightly pressrot.

ing the metal point'against the sensitive contact member in a direction at an lncline tothe plane of the contactsurface of such sensitive contact member.

2. Arleteetor for wireless apparatus comprising two contact devices, one. consisting ofa sensitive contact member and the other ofa metal point, and a light spring carry ing said metal polnt and arranged to press it against said sensitive contact member in I 11,-;

a direction inclined to the general plane of the sensitive contact member cont-act surface." I w r i 3. A detectOr fol; wireless apparatus, com

prising two contact devices, one of which at an incline to the ccntact surface of 3 the other 0f a metal point, ant} resilientmeans carrying such meta? point canine; and arranged press the same lighfiy against such sensitive Contact member in, a direction aid sensitive Contact membelf, said, real 1 means permitting a limited. Miami mtwement 0f the metal point (we? twc surface sf such sensit've contact T1221". I M m in test-imcny wl'lerebf," Iaffix my signw tum in the pres nee ofwvfinesses.

BEER MEN "J. MIESSNEFJ. Witnessw as 2 JIM-KNEE. Shawna Elmmm M. HOUGHTON. 

